Usage with Next.js

tip

If you’re using tRPC in a new project, consider using one of the example projects as a starting point or for reference: tRPC Example Projects

tRPC and Next.js are a match made in heaven! Next.js makes it easy for you to build your client and server together in one codebase. This makes it easy to share types between them.

tRPC includes dedicated tools to make the Next.js developer experience as seamless as possible.

Recommended file structure

Recommended but not enforced file structure. This is what you get when starting from the examples.

.
├── prisma # <-- if prisma is added
│   └── [..]
├── src
│   ├── pages
│   │   ├── _app.tsx # <-- add `withTRPC()`-HOC here
│   │   ├── api
│   │   │   └── trpc
│   │   │       └── [trpc].ts # <-- tRPC HTTP handler
│   │   └── [..]
│   ├── server
│   │   ├── routers
│   │   │   ├── app.ts   # <-- main app router
│   │   │   ├── post.ts  # <-- sub routers
│   │   │   └── [..]
│   │   ├── context.ts      # <-- create app context
│   │   └── createRouter.ts # <-- router helper
│   └── utils
│       └── trpc.ts  # <-- your typesafe tRPC hooks
└── [..]

Add tRPC to existing Next.js project

1. Install deps

yarn add @trpc/client @trpc/server @trpc/react @trpc/next zod react-query

• React Query: @trpc/react provides a thin wrapper over react-query. It is required as a peer dependency.
• Zod: most examples use Zod for input validation, though it isn’t required. You can use a validation library of your choice (Yup, Superstruct, io-ts, etc). In fact, any object containing a parse, create or validateSync method will work.

2. Create a tRPC router

Implement your tRPC router in ./pages/api/trpc/[trpc].ts. If you need to split your router into several subrouters, implement them in a top-level server directory in your project root, then import them into ./pages/api/trpc/[trpc].ts and merge them into a single root appRouter.

View sample router

import * as trpc from '@trpc/server';
import * as trpcNext from '@trpc/server/adapters/next';
import { z } from 'zod';
const appRouter = trpc.router().query('hello', {
  input: z
    .object({
      text: z.string().nullish(),
    })
    .nullish(),
  resolve({ input }) {
    return {
      greeting: `hello ${input?.text ?? 'world'}`,
    };
  },
});
// export type definition of API
export type AppRouter = typeof appRouter;
// export API handler
export default trpcNext.createNextApiHandler({
  router: appRouter,
  createContext: () => null,
});

3. Create tRPC hooks

Create a set of strongly-typed hooks using your API’s type signature.

// utils/trpc.ts
import { createReactQueryHooks } from '@trpc/react';
import type { AppRouter } from '../pages/api/trpc/[trpc]';
export const trpc = createReactQueryHooks<AppRouter>();
// => { useQuery: ..., useMutation: ...}

4. Configure _app.tsx

The createReactQueryHooks function expects certain parameters to be passed via the Context API. To set these parameters, create a custom _app.tsx using the withTRPC higher-order component:

import { withTRPC } from '@trpc/next';
import { AppType } from 'next/dist/shared/lib/utils';
import { AppRouter } from './api/trpc/[trpc]';
const MyApp: AppType = ({ Component, pageProps }) => {
  return <Component {...pageProps} />;
};
export default withTRPC<AppRouter>({
  config({ ctx }) {
    /**
     * If you want to use SSR, you need to use the server's full URL
     * @link https://trpc.io/docs/ssr
     */
    const url = process.env.VERCEL_URL
      ? `https://${process.env.VERCEL_URL}/api/trpc`
      : 'http://localhost:3000/api/trpc';
    return {
      url,
      /**
       * @link https://react-query.tanstack.com/reference/QueryClient
       */
      // queryClientConfig: { defaultOptions: { queries: { staleTime: 60 } } },
    };
  },
  /**
   * @link https://trpc.io/docs/ssr
   */
  ssr: true,
})(MyApp);

5. Make API requests

import { trpc } from '../utils/trpc';
const IndexPage = () => {
  const hello = trpc.useQuery(['hello', { text: 'client' }]);
  if (!hello.data) {
    return <div>Loading...</div>;
  }
  return (
    <div>
      <p>{hello.data.greeting}</p>
    </div>
  );
};
export default IndexPage;

caution

If you encounter problems with the required parameters in the hello endpoint using useQuery (in the example above { text: 'client' }), and you have used zod to validate them, make sure that your tsconfig.json file contains "strict": true and "strictNullChecks": true. If not add them or change their value to true

withTRPC() options

config-callback

The config-argument is a function that returns an object that configures the tRPC and React Query clients. This function has a ctx input that gives you access to the Next.js req object, among other things. The returned value can contain the following properties:

• Exactly one of these are required:

  • url your API URL.
  • links to customize the flow of data between tRPC Client and the tRPC-server. Read more.

• Optional:

  • queryClientConfig: a configuration object for the React Query QueryClient used internally by the tRPC React hooks: QueryClient docs
  • headers: an object or a function that returns an object of outgoing tRPC requests
  • transformer: a transformer applied to outgoing payloads. Read more about Data Transformers
  • fetch: customize the implementation of fetch used by tRPC internally
  • AbortController: customize the implementation of AbortController used by tRPC internally

ssr-boolean (default: false)

Whether tRPC should await queries when server-side rendering a page. Defaults to false.

responseMeta-callback

Ability to set request headers and HTTP status when server-side rendering.

Example

export default withTRPC<AppRouter>({
  config({ ctx }) {
    /* [...] */
  },
  ssr: true,
  responseMeta({ clientErrors, ctx }) {
    if (clientErrors.length) {
      // propagate first http error from API calls
      return {
        status: clientErrors[0].data?.httpStatus ?? 500,
      };
    }
    // cache full page for 1 day + revalidate once every second
    const ONE_DAY_IN_SECONDS = 60 * 60 * 24;
    return {
      'Cache-Control': `s-maxage=1, stale-while-revalidate=${ONE_DAY_IN_SECONDS}`,
    };
  },
})(MyApp);

Next steps

Refer to the @trpc/react docs for additional information on executing Queries and Mutations inside your components.